1. Field
The subject invention is in the field of devices used to produce acoustic energy, in particular diaphragms which, when activated, produce acoustic energy. For purposes of this disclosure, acoustic energy is the energy of waves in atmosphere which produce sound when perceived by ears of humans and animals and by electronic equipment such as microphones and associated amplifiers, speakers, etc. In particular, the subject invention is in the field of diaphragms for use on the chest pieces of stethoscopes. When a chest piece is placed on the surface of a human body the motions of the surface activate the diaphragm to generate acoustic energy which is transmitted to the user""s ears and perceived as sounds having specific, significant characteristics.
Such diaphragms operate in two modes. In one the rim or effective rims of the diaphragm is/are fixed and the functional characteristics of the diaphragm are determined by its physical characteristics. In a second mode the diaphragm is supported by flexible structure which is called a surround. In this mode the functional characteristics of the diaphragm are determined primarily by the physical characteristics of the surround. The subject invention is in the specific field of chest piece diaphragms operable in this second mode.
2. Prior Art
Prior art stethoscope diaphragms usable in the second mode are known to comprise a diaphragm or diaphragm subassembly and some type of retainer for attaching the diaphragm or diaphragm subassembly to the stethoscope chest piece. Examples of this prior art can be found in U.S. Patents 4,440,258 and 5,945,640. It is well known in the trade that (1) for these diaphragms to function as intended they must be correctly installed, (2) that it requires considerable experience and skill to correctly install the diaphragms, and (3) they can easily be installed with hard to detect imperfection, resulting in poor performance.
Therefore, the primary objective of the subject invention is to provide a stethoscope diaphragm assembly which operates in the second mode as defined above, and can be easily correctly installed with incorrect installation clearly obvious.
The subject invention is a diaphragm assembly for a stethoscope chest piece. The assembly comprises a diaphragm and a surround which are permanently attached to each other. The diaphragm is a plastic disc. The surround is elastomeric and a body of revolution having a rim portion which is relatively stiff because of its thickness and a membrane portion extending radially inward from the rim portion, the membrane portion being relatively flexible because it is relatively thin. The diameter of the diaphragm is smaller than the inside diameter of the rim portion so that when the diaphragm is adhesively concentrically attached to the membrane portion of the surround there is a circular portion of the membrane portion between the diaphragm and the rim portion. The rim portion is grooved on its inside diameter and the groove engages a ridge on the chest piece to hold the diaphragm assembly in place. The circular portion of the membrane allows the diaphragm to translate on its centerline to operate in the second mode as noted above.